1.\" Copyright (c) 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)tcsendbreak.3 8.1 (Berkeley) 6/4/93 29.\" 30.Dd January 11, 2017 31.Dt TCSENDBREAK 3 32.Os 33.Sh NAME 34.Nm tcsendbreak , 35.Nm tcdrain , 36.Nm tcflush , 37.Nm tcflow 38.Nd line control functions 39.Sh LIBRARY 40.Lb libc 41.Sh SYNOPSIS 42.In termios.h 43.Ft int 44.Fn tcdrain "int fd" 45.Ft int 46.Fn tcflow "int fd" "int action" 47.Ft int 48.Fn tcflush "int fd" "int action" 49.Ft int 50.Fn tcsendbreak "int fd" "int len" 51.Sh DESCRIPTION 52The 53.Fn tcdrain 54function waits until all output written to the terminal referenced by 55.Fa fd 56has been transmitted to the terminal. 57.Pp 58The 59.Fn tcflow 60function suspends transmission of data to or the reception of data from 61the terminal referenced by 62.Fa fd 63depending on the value of 64.Fa action . 65The value of 66.Fa action 67must be one of the following: 68.Bl -tag -width "TCIOFF" 69.It Fa TCOOFF 70Suspend output. 71.It Fa TCOON 72Restart suspended output. 73.It Fa TCIOFF 74Transmit a STOP character, which is intended to cause the terminal to stop 75transmitting data to the system. 76(See the description of IXOFF in the 77.Ql Input Modes 78section of 79.Xr termios 4 ) . 80.It Fa TCION 81Transmit a START character, which is intended to cause the terminal to start 82transmitting data to the system. 83(See the description of IXOFF in the 84.Ql Input Modes 85section of 86.Xr termios 4 ) . 87.El 88.Pp 89The 90.Fn tcflush 91function discards any data written to the terminal referenced by 92.Fa fd 93which has not been transmitted to the terminal, or any data received 94from the terminal but not yet read, depending on the value of 95.Fa action . 96The value of 97.Fa action 98must be one of the following: 99.Bl -tag -width "TCIOFLUSH" 100.It Fa TCIFLUSH 101Flush data received but not read. 102.It Fa TCOFLUSH 103Flush data written but not transmitted. 104.It Fa TCIOFLUSH 105Flush both data received but not read and data written but not transmitted. 106.El 107.Pp 108The 109.Fn tcsendbreak 110function transmits a continuous stream of zero-valued bits for four-tenths 111of a second to the terminal referenced by 112.Fa fd . 113The 114.Fa len 115argument is ignored in this implementation. 116.Sh RETURN VALUES 117Upon successful completion, all of these functions return a value of zero. 118.Sh ERRORS 119If any error occurs, a value of -1 is returned and the global variable 120.Va errno 121is set to indicate the error, as follows: 122.Bl -tag -width Er 123.It Bq Er EBADF 124The 125.Fa fd 126argument is not a valid file descriptor. 127.It Bq Er EINVAL 128The 129.Fa action 130argument is not a proper value. 131.It Bq Er ENOTTY 132The file associated with 133.Fa fd 134is not a terminal. 135.It Bq Er EINTR 136A signal interrupted the 137.Fn tcdrain 138function. 139.It Bq Er EWOULDBLOCK 140The configured timeout expired before the 141.Fn tcdrain 142function could write all buffered output. 143.El 144.Sh SEE ALSO 145.Xr tcsetattr 3 , 146.Xr termios 4 , 147.Xr tty 4 , 148.Xr comcontrol 8 149.Sh STANDARDS 150The 151.Fn tcsendbreak , 152.Fn tcflush 153and 154.Fn tcflow 155functions are expected to be compliant with the 156.St -p1003.1-88 157specification. 158.Pp 159The 160.Fn tcdrain 161function is expected to be compliant with 162.St -p1003.1-88 163when the drain wait value is set to zero with 164.Xr comcontrol 8 , 165or with 166.Xr ioctl 2 167.Va TIOCSDRAINWAIT , 168or with 169.Xr sysctl 8 170.Va kern.tty_drainwait . 171A non-zero drain wait value can result in 172.Fn tcdrain 173returning 174.Va EWOULDBLOCK 175without writing all output. 176The default value for 177.Va kern.tty_drainwait 178is 300 seconds. 179